Mystery Boiler from hell

After all sorts of trouble...it was working, circulating...every radiator heating....I was convinced that it had been a lack of water and pressure, it ran great for hours...then we woke up cold. The aquastat askes the pump to circulate at the call for heat...whether or not the blower and burners are on..was working last night for the first time in 5 weeks....now it is back to the 3 or 5 minutes to heat up and shuts down....I rebled the all the radiators, but still only 3 to 5 minutes and it shuts down cuz it is to limit..

Is it a lack of water in the tank itself? I am no expert so get your "grain of salt" out. It would seem to me that you could heat a small amount of water and a lot of air to the stop temp in 4 to 5 minutes, but not a large amount of water. I would try adding water to the tank, opening the release, see if air comes out, then adding more. If it is still circulation, what pump would be broke? The fuel pump? if so $5.95 for a gage and couple bucks more for the male/male threaded 3/8 connect.

This all started with a tech coming out and saying he didn't know what was wrong, everything tested ok...not sure how to run the pump pulled....it is a taco007 with a cart. Guess I get to pay again....it has beat me. Grandkids coming to a cold house.

Well, I think we had two issues...Low water and air AND an intermediate short in the wiring at the pump. My step son as here for Christmas, he is a journeybman Electrician. We thought it was the pump and he confirmed and was able to "fix" it until we can replace it.
Thanks for all the input..it all helped.